Reversing brush-gear for dynamo-electric machines



H. D. ROHMAN. REVERSING BRUSH GEAR FOR DYNAMO ELECTRIC MACHINES.

APPLICATION FILED OCT-9,1917. 1,349,584. P t n ed Aug- 17, 0.

2 SHEE S S HE l H. D. ROHMAN. REVERSING BRUSH GEAR FOR DYNAMO ELECTRIC MACHINES.

APPLICATION FILED OCT. 9, I J

Patemed Aug. 17 1920 2 SHEETSSHEET 2.

UNITED STATES PATENT OFFICE.

HARRY D. BOHMAN, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO

J. STONE & COMPANY, LIMITED, 01 DEPTFORD, ENGLAND.'

REVEBSING BRUSH-GEAR FOR DY NAMO-ELECTRIC MACHTNES.

Application filed October 9, 1917.

To all whom. it may concern Be it known that I, HARRY D. ROHMAN, a citizen of the Republic of Switzerland, residing at New York city, in the county of New York and State of New York. have invented certain new and useful Improvements in Reversing Brush-Gears for Dynamo-Electric Machines, of which the following is a specification.

This invention relates to improvements in reversing brush gears for dynamo electric machines, particularly those employed in electric train lighting and heating service, and it has for one of its primary objects the provision of an improved gear of simple construction in which pitting of the ball races is eliminated and the strain on the hall races greatly diminished.

My invention is of especial value in connection with brush rigging which swings through the full polar arc. such for example as is shown in co-pending application, Serial Number 148,930, filed February 16, 1917, and in the drawings I have shown my invention as applied to a brush rigging of this type, attention being directed to the said co-pending application for a more detailed illustration and description.

Of the drawings, Figure 1 is an end View of a car lighting dynamo and brush rigging: Fig. 2 is a section taken on the line II-JI of Fig. 1, and Fig. 3 is a sectional view of a detail of my invention drawn on a larger scale.

Referring to the drawings, numeral 7 denotes the magnet frame of the dynamo in which the armature spindle or shaft 8, the commutator 9 and the armature 10 are rotatably mounted in suitable bearings. A front head or ring 11 is secured to the outer face of the casing 7 which accommodates the forward end of the armature shaft with its hearing A, such bearing being of the ball-bearing type. The brushes, generally indicated at B and C. are mounted in the usual brush holders 12, such brush holders being carried in the rocker 13. The rocker 13 comprises an outer ring-like member and an inner two-piece ball race 14. The ring extension 15 of the front head 11 is provided with a ball r ce 16, and balls 17 are interposed between t e two ball races. (See Figs. 2 and 3.) The specific arrangement of the brushes, leads, and connections for the external circuit, shown in Fig. 1, con- Specification of Letters Patent.

Patented Aug. 17, 1920.

Serial No. 195,510.

stitutes no part of the present invention and is described and claimed in the aforementioned co-pending application, and it is sufficient for the purposes of this specification to state that the arrangement is such that upon starting or reversing of the train the friction of the brushes on the commutator causes the rocker 13 to reverse 180, or through the full polar arc, in a direction corresponding to that of the train travel, thus reversing the position of the brushes and maintaining constant polarity in the external circuit regardless of the direction of rotation. It is of course to be understood that stops are provided to limit the movement of the brush rocker. One such stop is shown at 18 in Fig. 1.

The pitting of the ball saces hereinbefore referred to results chiefly from the excessive vibration and chattering which occurs when the train is running at higher speeds, and I overcome this difliculty by the provision of a magnetically operated locking device which is normally ineffective when the train is not moving, but which is actuated to securely hold the brush rocker after it is moved to either of its two operative positions so as to relieve the ball races of strain and to prevent chattering and vibration. This electromagnetic device comprises a ring 19 mounted on the rocker 13 and provided with an inturned lip 20. At several points the ring 19 is slotted as at 21 for the reception of pins 22 which are mounted in the rocker 13. By this arrangement the locking ring rotates with the brush rocker but is capable of a limited movement toward and from the shoulder 23 of the front head 11. A winding 24 is located in the face of the shoulder 23, in opposition to the lip 20 of the ring 19 and is preferably connected in shunt across the brushes.

The operation is as follows: Upon starting of the train in either direction of running, the brush rocker 13 is moved through the full polar arc until it comes up against the stops 18, the brush rocker being held in the respective operative position by the friction of the brushes on the commutator. As the dynamo voltage builds up, the coil 24 becomes energized and attracts the lip 20 against the shoulder 23, and the ring 19 through the medium of the pins 22 securely holds the brush rocker in position and prevents the chattering and vibration which causes pitting oi the ball races, and in addition relieves the ball races of a portion of the strain. The arrangement is simple, efiective in operation and adds greatly to the life of the bearings.

I claim:

1. A brush gear for dynamo electric machines comprising in combination a brush rocker support, a reversible brush rocker mounted thereon, brushes on the rocker, a bearing interposed between said support and said brush rocker, a locking armature inde pendent of the brushes non-rotatably but slidably associated With said brush rocker, and means cooperating therewith to lock the brush rocker including a Winding adapted to attract said armature.

2. brush gear for dynamo electric machines comprising in combination a brush rocker support, a brush rocker rotatably carried thereon, brushes on the rocker, a locking armature independent of said brushes mounted on said brush rocker'for transverse movement with respect thereto but not rotary movement, and a Winding for attracting said armature.

3. A brush gear for dynamo electric machines comprising in combination a shouldered brush rocker support, a brush rocker rotatably mounted thereon, a slotted armature ring mounted on said brush rocker and adapted to cooperate With said shoulder to lock the bruch rocker, a pin carried by the brush rocker projecting in said slot, and a Winding in the face of said shoulder adapted to attract said. armature.

In testimony whereof I have hereunto signed my name i H. n. ROI-IMAN. 

